Rare black moon rises over Colorado on Monday

The blue moon’s equally rare cousin, the black moon, will rise in the Colorado sky Monday night, but you won’t be able to see it.

While a blue moon is the second full moon in a month, the black moon is the second new moon in a month—or the third new moon in a season with four instead of a typical three— according to time and date.

New moons are fairly common, occurring about once every four weeks, but they only appear twice in the same month about every 29 months, according to the time and date. The next monthly black moon won’t happen before 31 August 2027.

Seasonal black moons are slightly rarer, occurring approximately once every 33 months. The next seasonal black moon will rise on August 23, 2025.

The second new moon in December will rise on Monday at 15:27 mountain time or 22:27 universal time, according to the US Naval Observatory.

Unfortunately, like any other new moon, tonight’s black moon will be invisible in the sky.

New moons are created when the moon is between the earth and the sun, meaning the moon’s illuminated side faces away from the earth and appears to be missing from the sky, according to NASA.